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Don't throw away your laptop yet, but there's a promising new high-tech invention being announced this week. The most dense computer memory circuit ever fabricated was unveiled by scientists in California.

The team of experts at the California Institute of Technology (Caltech) and the University of California, Los Angeles (UCLA) who developed the 160-kilobit memory cell say it has a bit density of 100 gigabits per square centimeter, a new record.

The cell is capable of storing a file the size of the United States' Declaration of Independence with room left over, Caltech said in a statement.

But the chances of the unit being used in a laptop any time soon is remote, said Caltech chemistry professor James Heath, who led the research.

"It's the sort of device that Intel would contemplate making in the year 2020," says Heath, who is the Gilloon Professor at Caltech. "But at the moment it furthers our goal of learning how to manufacture functional electronic circuitry at molecular dimensions."

Whether the 2020 date is viable depends on the validity of Moore's law, which states that the complexity of an integrated circuit typically will double every year, he said.

However, manufacturers currently can see no clear way of extending the miniaturization beyond the year 2013, the Caltech-UCLA team writes in an article that will appear in the journal Nature on Thursday.

"Whether it's possible to get this new memory circuit into a laptop, I don't know," said Heath. "But we have time."

The capability to manufacture electronic circuitry at such extreme dimensions opens up a host of new applications, ranging from extremely sensitive chemical and biological sensors, energy-efficient logic circuits, and a class of high-performance energy-conversion materials known as thermoelectrics.

The 160,000 memory bits are arranged like a large tic-tac-toe board: 400 silicon wires crossed by 400 titanium wires, with a layer of molecular switches sandwiched between the crossing wires. Each wire crossing defines a bit, and a single bit is only 15 nanometers wide, or about one ten-thousandth the diameter of a human hair. By contrast, the most dense memory devices currently available are approximately 140 nanometers in width.

The molecular switches, called rotaxanes, comprise two interlocking components--a molecular ring encircling a dumbbell-shaped molecule--that together are similar to a wedding band on a finger. When the molecular switch is electronically triggered, the ring slides between two locations on the dumbbell. Switching, then, arises from the different conductivities of the molecular switch with respect to the ring position.